The Organic Light Emitting Diode (OLED) is a display technology which has great prospects for development. It does not only possess extremely excellent display performance but also properties of self-illumination, simple structure, ultra thin, fast response speed, wide view angle, low power consumption and capability of realizing flexible display, and therefore is considered as “dream display”. It has been favored by respective big display makers and has become the main selection of the third generation display element.
An OLED display device generally comprises a substrate, an anode located on the substrate, an organic emitting layer located on the anodes, an electron transport layer located on the organic emitting layer, and a cathode located on the electron transport layer. As working, the Hole from the anode and the Electron from the cathode are injected to the organic emitting layer, these electrons and the holes are combined to generate excited electron-hole pairs, and the excited electron-hole pairs are converted from the excited state to the ground state for achieving illumination.
In the manufacture process of the OLED display device, for decreasing the process difficulty and the color and the brightness deterioration of the luminescent material, the display method of four colors sub pixels comprising Red(R), Green(G), Blue(B), White(W) is commonly utilized. That is so called WRGB OLED display. The working principle of the WRGB OLED display is to utilize the white organic light emitting diode to emit light and the color filters to transfer the white light to be red light, green light and blue light for realizing the OLED display device with WRGB four colors display.
As shown in FIG. 1, in the pixel structure of the present WRGB OLED, the utilized organic light emitting diodes are white organic light emitting diodes. The red, the green and the blue sub pixels respectively comprise filters 300 transferring the white light to be red light, green light and blue light. The white sub pixels remain to emit white light as what they do without filters 300. Therefore, the layer where the white organic light emitting diode of the white sub pixel is formed is lower than the layer where the organic light emitting diodes of the red/green/blue sub pixels are formed. The first electrode layer 100 in the white sub pixel is also lower than the first electrode layers 100′ of the red, the green, the blue sub pixels. The vertical distance y1 between the first electrode layer 100 and the bottom layer wiring 400 of the white sub pixel is smaller than the vertical distance y2 between the first electrode layer 100′ and the bottom layer wiring 400 of the red, the green, the blue sub pixels. The pixel structures of the blue sub pixel and the white sub pixel in FIG. 1 are illustrated for explanation.
In practical manufacture process, the impurity substance can be involved due to the improper treatment (such as photo residual glue, unclean etching), and easily cause effect to the white sub pixel of which the vertical distance between the bottom layer wiring 400 and the first electrode layer 100 is smaller. The overlap area 200 of the bottom layer wiring 400 and the first electrode 100 can cause the short circuit or overcurrent between the bottom layer wiring 400 and the first electrode 100.